Thread rolling attachment



June 13, 1961 E. w. BRINKMAN 2,987,945

THREAD ROLLING ATTACHMENT Filed Nov. 23,. 1956 2 Sheets-Sheet 1 T? I W n I .4190 I04 I 92 INVENTOR.

RL m BR/NKMA/V H0. 1.

ATTORNEY June 13, 1961 E. w. BRINKMAN THREAD ROLLING ATTACHMENT 2 Sheets-Sheet 2 Filed NOV. 25, 1956 m m m m EARL H. ERIN/(MAN A TIC/MIEY Filed Nov. 23,1956, Ser. No. manor Claims. c1. 80--6) This invention relates to a pattern rolling attachment arranged to be operated from the cross slide of an automatic screw machine or the like, and for rolling knurls, screw threads, splines, teeth, in the case of small pinions, and the like on work pieces.

Since the rolling of patterns such as knurls, screw threads, and the like on metal stock is a cold-forging process in which the patterns are formed by displacement of the metal from the stock, considerable side pressure is applied to the stock during the process. Conventionally, the rollers of such attachments are advanced into the work in a fixed, preset condition, and a large side pressure is developed that tends to bend the work. To overcome the tendency toward bending, conventional attachments have required the use of a work support to oppose the side thrust of the work. Such a support occupies a spindle or end working position of the screw machine which otherwise could be utilized for drilling, tapping or any other extra machining operation that might be required.

To overcome this drawback and other limitations of conventional attachments, applicant devised an improved pattern rolling attachment in which two pattern forming rolls are held in open or separated position while being advanced from inoperative position to the center line of the work to straddle it, after which the rolls are closed against the opposite sides of the work. In this way, unbalanced side pressure which might bend the work is eliminated or minimized. A train of gears interconnects the two pattern rolls to maintain them in synchronism. The details of the construction of this improved attachment are disclosed in 'applicants copending patent application, Serial No. 743,460, filed June 20, 1958.

In applicants improved attachment, as described more fully in the said copending application, the pattern rolls are rotatably supported on the lower ends of a pair of support arms that are pivoted intermediate their ends on a slide that can reciprocate only over a limited distance. At their upper ends, the support arms are connected to a cam-operated toggle. In the inoperative, at-rest position, the slide is raised and the support arms are pivoted so that their lower ends, which carry the pattern rolls, are swung apart. In operation, the toggle is caused to move downwardly simultaneously with the slide over the limited reciprocal path over which the slide can travel. After the movement of the slide is stopped, the downward movement of the toggle is continued. As the toggle moves down, the upper ends of the two support arms are forced apart, and the lower ends are forced together, to move the two pattern rolls together to engage the work along the center line of the work.

The two pattern rolls are interconnected for synchronous rotation by a gear train. The gear train is made up of two roll gears, two idler gears, and a timing gear. One roll gear is secured coaxially with each pattern roll and is mounted for rotation upon rotation of the pattern roll. The idler gears are mounted to rotate freely about the pivots of the support arms in engagement with the roll gears, respectively. The timing gear meshes with both idler gears and rotatably connects them together. Rotation of the work spindle causes rotation of the pattern rolls when they are engaged with the work. When the nited States Patent pattem-forming rolls rotate, they are maintained in synchronism by the gear train comprising the roll gears, idlers, and the timing gear.

In using the attachment of a'pplicants above-mentioned patent application, difficulty was sometimes experienced with slight mis-alignments of the thread-forming rolls. This would result in an imperfect product.

An object of the present invention is to provide a pattern-rolling attachment of the character described for an automatic screw machine or the like having simple means incorporated therein for compensating for any slight starting mis-alignment of the thread rolls.

Another object of the invention is to provide a device of the character described having means for aligning the thread rolls initially as well as for compensating for any slight mis-alignment of the thread-rolls which may take place during rolling. i

Another object of the invention is to provide a compensating device for a thread rolling attachment for an automatic screw machine, that will always return' the thread rolls to an initial setting regardless of any misalignment that occurs during rolling.

A further object of the invention is to provide a synchronizing gear train for a pattern rolling attachment for an automatic screw machine, that will permit of'rapid and easy alignment of the pattern forming rolls.

Other objects of the invention will be apparent to those skilled in the art from the following specification and the appended drawing in which is'illustrated one specific embodiment of the invention.

In the illustrated embodiment of the invention, as in my prior application previously identified, there is a roll gear mounted coaxially with each thread roll to rotate upon rotation of the thread roll, and there are a pair of idler gears freely rotatably mounted to rotate on the ful crum of the support arms in engagement with the roll gears. In the improved construction of the present invention, however, the two idler gears mesh with separate, coaxial, axially-spaced timing gears that are rigidly secured on separate concentric shafts. The shafts are connected through a compensating assembly including a pair of collars that are secured, respectively, to the two shafts. An annular channel isformed in the face of one of the two collars. A 'pin is secured to each collar to extend into the annular channel. Two powerful helical coil springs, of equal size, are seated in the channel, and one spring is interposed between one pair of opposed sides of the two pins; and the other spring is interposed between the other pair of opposed sides of the two pins. One of the pins may be wedge-shaped to provide flat seating surfaces at its opposite sides for the ends of the two springs that seat on that pin.

With this construction, when the pattern rolls are properly aligned, the two timing gears rotate simultaneously, as a unit, since the concentric shafts are secured together through the compensating assembly just described. However, when there is any misalignment for any reason between the two pattern rolls, the powerful coil springs in the compensating assembly will tend immediately to accelerate the roll gear that tends to lag, so that this misalignment will be immediately compensated .for and offset. When the pattern forming operation is completed, and the pattern rolls are moved away from the work, the springs, the two shafts, the two timing gears mounted thereon, and the pattern forming .rolls, return to their original positions. I

If the misalignment is due to some temporary cause during rolling, when the pattern rolls are moved away from the work, the springs force the timing gears back into proper alignment.

In the drawings:

. on the bolt.

FIG. 1 is a side elevation, partly broken away, showmg a pattern rolling attachment constructed according to one embodiment of the present invention, and showing, also fragmentarily, cooperating parts of a screwthreading machine on which it is used, the pattern rolling attachment being shown in an intermediate stage in its cycle of operation;

FIG. 2 is a front elevation thereof;

FIG. 3 is a diagrammatic representation on an enlarged scale of the pattern forming rolls and the work,

i with the rolls shown in their open position with their axes aligned, straddling the work;

FIG. 4 is a second diagrammatic representation on the same scale showing the rolls advanced from the straddling position to a closed position in engagement with the work, with the axes of the rolls aligned with the center line of the work;

FIG. 5 is a side elevation on the same scale of a thread-forming pattern roll;

FIG. 6 is a section of the attachment taken on the line 66 of FIG. 7, looking in the direction of the arrows;

FIG. 7 is a section through the attachment taken on the line 77 of FIG. 6, looking in the direction of the be used on conventional automatic screw machines and lathes, it is shown in the drawings mounted on a Davenport automatic screw machine, of which only a fragment thereof is illustrated.

is engaged in the bore 63 of the slide. A coil spring 72 is mounted in the bottom of the bore 63 in the slide and is interposed between the bottom of the bore and the sleeve 70. The sleeve70 projects upwardly from the slide, around the bolt 62, and engages against the undersurface of the yoke 38. The spring 72 constantly presses the sleeve 70 outwardly from the bore 63 against the yoke to maintain a given spaced relation between the slide and the yoke.

The slide 60 has an arm 74 that projects laterally over the slide base 76. A screw 78 is adjustably threaded in the arm 74'and is locked in any adjusted position by a lock nut 80. The adjustable bolt 78 engages a stop-pin 8-1 that is secured in a recess 82 in the slide base 76.

Engagement of screw 78 with pin 81 limits the downward movement of the slide.

The rocking arms 54 and 56 are pivotally mounted on -studs 84 or 86, respectively, that are fastened the slide 60. Pattern forming rolls 88 and 90, respectively,

are secured rotatably on the lower ends of the rocking arms 54 and 56 respectively. The pattern forming rolls are mounted to be freely rotatable on studs 89 and 91,

respectively, that are secured in the arms 54, 56, re-

spectively. These rolls are adapted to be driven upon contact with the rotating workpiece W, which is driven through a rotating collet 92 in the conventional manner.

A gear 100 (FIG. 7) is mounted coaxially with the pattern-forming roll 88 and is rigidly secured thereto.

- An idler gear 102 is freely rotatably mounted on the stud a spring compensating device of the present invention can 84 and meshes with the roll gear 100. A gear 104 is mounted coaxially with the pattern forming roll 90, and is rigidly secured thereto, as by face clutch teeth, see FIG. 6. A second idler gear 106 is freely rotatably mounted on the stud 86 to mesh with the roll gear 104.

To maintain the pattern-forming rolls 88 and 90 in I synchronism when they are rotated in engagement with Referring now in detail to the drawings, the screw machine comprises the usual frame 10 (FIG. 1), in which there is mounted a rotary cam 11 that is secured on a motor-driven timing cam shaft 12 that is properly shaped to effect the several operations, that are to be performed the rotating work W, the idler rolls 102 and 106 respectively are interconnected by a pair of timing gears 108 and 110 that are mounted on inner and outer concentric shafts by the machine, in proper timed sequence. The cam 11, 1

operating through a cam follower 14, reciprccates a connecting rod 16, that is pivotally connected to one arm 18 of a lever 19 that is secured to a shaft 20. The other arm 24 of the lever 19 is pivotally connected to the stem 26 of a T-shaped link 28 (FIG. 2). The shaft.

20 is journaled in bearings 22' respectively that are carried on the frame 10.

The ends of the cross-arms 30 of this link, respectively (FIG. 2) are pivotally connected respectively to 112 and 114, respectively (FIG. 6).

The timing gear 110 is integral with or otherwise fixedly secured to the outer tubular shaft 114. The timing gear 108 is integral with or otherwise fixedly secured to the inner shaft 112.

The outer shaft 114 is freely rotatably supported on the inner shaft 112, and is journaled in a bushing 118 (FIG. 6) that is mounted in a support bracket 120 that is secured to the slide by a nut 123 and bolt 122. The bolt 122 is mounted in a sleeve-like protuberance I25 of slide 60.

The tubular shaft 114 protrudes outwardly through the bushing 118 from the face of the support bracket 120,

the upright arms 34 of a yoke 38. An eye-bolt 40 is r V secured on the body of the yoke intermediate its arms by a fixed pivot pin 42. The eye bolt 40 cooperates with a double nut 44 and a second eye bolt 46 to form a turnbuckle.

, The second, lower eye bolt 46 receives a bolt 48 that 1 functions as a pivot pin for the toggle arms 50 and 52 v ed rod 62 extends into a circular bore 63 (FIG. 1) in the slide 60, and at the bottom of the bore the lower end of the threaded rod is screwed into a threaded aperture .64 in the slide. At its upper end the threaded rod 62 passes through a clearance hole 66 in the yoke 38,

. and a pair of nuts 68 are secured on the protruding upper end of the threaded rod 62 to limit the downward movement of the rod with respect to the yoke 38.

A sleeve is mounted on the threaded rod 62' and while the inner shaft protrudes beyond the outer shaft A collar or sleeve 128 is mounted on the projecting end of the tubular shaft 114, and is secured thereto by a pin or set screw 130. The inner end face of the collar 128 (FIG. 9).

V abuts against the support bracket 120. The outer end face of collar 128 has an annular channel or recess 132 A bushing 149 is mounted on the shaft 114 in the channel. A cylindrical pin is mounted in the collar 128 and projects forwardly into the channel 132.

A collar 142 (FIG. 6) is mounted on the projecting portion of the inner shaft 112. A screw 146 threads through the'collar 142 to engage in a shallow circumferential channel 148 in the projecting portion 126 of the shaft 112 to hold collar 142 on shaft 112 while allowing relative rotation between this collar and this shaft. A wedge-shaped pin (FIGS. 6 and 9) is mounted in the collar 142 to extend rearwardly into the recess 132 in the collar 128.

A pair of powerful helical coil springs 150 are disposed t in the annular channel 132, between the pins 140 and 145. These springs seat at adjacent ends on the opposite fiat sides of the wedge-shapedpin '145. At their opposite ends they seat against opposite sides of pin 140.

In the operationof the pattern rolling attachment, as the timing shaft .12 of the screw machine rotates the cam 11, the high area thereon moves the rod 16 toward the upper left (FIG. 1). The rod 16 thereupon elevates the left arm 18 of the lever 19, rockingv the right lever arm 24 downward. The downward movement of the right lever arm 24 acts through the link 28 and the yoke 38 to lower the toggle joint and the slide 60, until the stop bolt 7-8 engages the stop pin 82 (FIG. 1), at which time downward movement of the slide is stopped, while downward movement of the yoke and the toggle joint is continued. At the instant the movement of the slide is stopped, the thread rolls 88 and 90 have been lowered to the horizontal center line of the work W and straddle it, as shown in FIG. 3.

Further downward movement of the lever arm 24, acting through the link 28 and the yoke 38, forces the toggle joint downward to pivot the rocking arms 54 and 56 respectively about their respective fulcrums 84 and 86. The thread rolls 88 and 90 are thereby forced inward into the opposite sides of the work, as shown in FIG. 4. The work, which is held in the rotating collet 92, rotates the engaged thread rolls to roll threads into the work. Since the thread rolls 88 and 90 are interconnected by the train of gears 100, 102, 108, 110, 106, and 104, the thread rolls are driven in synchronism. The two timing gears 108 and 119 are interconnected through their shafts by the compensating assembly, which includes pins 140 and 145 and helical coil springs 150. If one of the thread rolls 88, 90 starts to drive ahead of the other for any reason, the timing train connected to that thread roll will apply pressure through the associated pin 140 or 145 to the springs 150; and the springs 150 will apply compensating pressure through the other pin 140 and 145 and the other timing train to rotate the other thread roll 88 or 90, as the case may be, to compensate for the misalignment.

The cam 11 and the related parts hold the thread rolls 88 and 90 against the work until the threads are completely formed therein. The cam will thereupon have been rotated so far that its active surface falls away, so that the rod 16 proceeds to move toward the lower right. This causes the right arm 24 of lever 19 to rise, carrying the link 28 and the yoke 38 upward. The toggle joint is elevated, and the lower ends of the rocking arms 54 and 56 swing outward away from the work, carrying the thread rolls with them, to resume the straddling position shown in FIG. 3. As the lever arm 24 continues to move up, the yoke engages the check nut 68 and elevates the rod 62, and with it the slide 60. The slide acting through the fulcrum bolts 84 and 86, together with the toggle joint acting through the rocking arms 54 and 56, lifts the thread rolls 88 and 90 clear of the work W. At the zenith of the elevation of the right lever arm 24, the attachment is in its normal or rest position, in readiness to repeat its described cycle of operation.

Where there has been any misalignment between the thread rolls, either initially, or that occurred during the rolling of the work, one of the springs will compress to permit relative rotation between the timing gears 108 and 110. As soon as the thread rolls are withdrawn from the work, however, the spring will expand and press against the wedge-shaped pin 145 to return the timing gears and the thread rolls to their original position, so that rolling will always start in the same place, and so that the compensating device is in readiness to compensate for any minor error in alignment during the rolling operation.

While repeated reference has been made in the above description to the use of thread rolls 88 and 90 as the pattern forming rolls, it will be understood that various other pattern forming rolls, such as knurling rolls, can be employed in the present attachment and that the full advantage of the compensating device is obtained therewith.

While the invention has been described in connection with a specific embodiment thereof, then, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention what I claim is:.

1. In apparatus for rolling a pattern on a rotating workpiece, and comprising a rectilinearly reciprocable slide, a pair of pattern-forming rolls, separate means for separately supporting said rolls for rotation about spaced parallel axes which extend at right angles to the plane of reciprocation of said slide, means connecting said supporting means to said slide to move with said slide, means for moving said slide rectilinearly in one direction to move said rolls to a position in which they straddle the workpiece with the axes of the rolls and workpiece lying in a common plane extending at right angles to the plane of reciprocation of said slide, means for thereafter moving said separate supporting means toward each other to engage said rolls with the workpiece at opposite sides of the workpiece, and means for rotating the rolls in timed relation while engaged with the workpiece, the improvement comprising a gear secured to each roll to rotate upon rotation of the roll, said gears being identical, a pair of identical coaxial timing gears, one of which is connected to each of the first-named gears to rotate upon rotation of the connected first-named gear, and two identical springs interposed between the two timing gears and resiliently resisting rotation of the timing gears relative to one another in both directions, thereby to resist angular misalignment of said rolls.

2. In apparatus for rolling a pattern on a rotating workpiece, and comprising a rectilinearly reciprocable slide, a pair of arms pivotally mounted on said slide for movement toward and away from one another about spaced parallel axes extending at right angles to the plane of reciprocation of said slide and disposed intermediate the ends of the respective arms, a pattern-forming roll rotatably mounted on each arm adjacent, respectively, the corresponding ends of said arms for rotation about an axis parallel to the respective axis of swing of its arm, actuating means for eifecting movement of said slide rectilinearly in one direction, means for limiting said movement so that it is stopped with said rolls in a position in which said rolls straddle the workpiece with the axes of the rolls and workpiece lying in a common plane extending at right angles to the plane of reciprocation of said slide, lost-motion means connecting said actuating means to said arms and operative, upon stoppage of said slide movement in said one direction and upon continued operation of said actuating means to move said arms toward one another to engage said rolls with the workpiece, said lost motion means being connected to said arms adjacent the ends thereof opposite the ends ad'- jacent which said rolls are mounted, and means for rotating said rolls in timed relation while engaged with the workpiece, the improvement comprising a gear secured to each said roll coaxially therewith to rotate upon rotation of the roll, said gears being identical, an idler gear meshing with each first-named gear and mounted, respectively, coaxially with the pivots of the two arms for rotation about axes parallel to the axes of said rolls, said idler gears being identical, a pair of identical coaxial timing gears mounted for rotation about axes parallel to the axes of said rolls and meshing respectively, with the two idler gears, and identical springs interposed between the two timing gears and resiliently resisting rotation of the two timing gears relative to one another in both directions, thereby to resist angular misalignment of said rolls.

3. Apparatus for rolling a pattern on a rotating work- '7 piece comprising a pair of rotatable pattern-forming rolls that are mounted to engage a rotating workpiece on opposite sides thereof to be rotated by said workpiece, a pair of gears one of.which is secured to each pattern-forming roll to rotate upon rotation of the roll, a pair of coaxial shafts mounted one within the other, gearing connecting one of the two shafts with one of the first-named gears, gearing identical to the first-named gearing connecting the other of said two shafts with the other of the two firstnamed gears, and a pair of equal springs interposed between the two shafts to resiliently resist rotation of the two shafts relative'to one another in bothv directions,

thereby to resiliently urge both shafts to rotate together in both directions.

4. Apparatus for rolling a pattern on a rotating workpiece comprising a pair of rotatable pattern-forming rolls that are mounted to engage a rotating workpiece on opposite sides thereof to be rotated by said workpiece, a pair of gears one of which is secured to each pattern-forming roll to rotate upon rotation of the roll, an idler gear meshing with each of the first-named gears to be rotated thereby, a timing gear meshing with each idler gear, a pair of coaxial shafts mounted one within the other, one of said timing gears being secured to one of said shafts, and the other timing gear being secured to the other of said shafts, the inner of said two shafts projecting at one end axially beyond the corresponding end of the other shaft, a pair of confronting collars rigidly secured on said corresponding ends of the two shafts, respectively, one of said collars having an annular channel therein confronting the opposed end face of'the other collar, an axiallydirected pin secured in each of said collars and engaging in said channel, and a pair of coil springs disposed in said channe-L-one spring being interposed between the two pins at one side thereof and the other spring being interposed between the two pins at the opposite sides thereof, said springs being equal and resiliently resisting relative rotation of. said collars and of the shafts in both directions.

5. Apparatus as claimed in claim 4 wherein one of said pins is of triangular shape in cross-section with its apex directed toward the common axis of said shafts, and said two springs seat at adjacent ends against opposite flat sides of said one pin.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,897 Scott Nov. 16, 1954 560,930 Rau May 26, 1896 1,678,924 Strindberg July 31, 1928 1,721,729 Davenport July 23, 1929 2,071,885 Lewis et al Feb. 23, 1937 2,323,324 Hanson July 6, 1943 2,355,132 Afileclt Aug. 8, 1944 2,407,144 Edwards Sept. 3, 1946 2,694,935 Roehri Nov. 23, 1954 2,748,633 Bedker June 5, 1956 2,771,799 Batchelder Nov. 27, 1956 FOREIGN PATENTS 753,845 Great Britain Aug. 1, 1956 

